In conventional mechanical steering systems with hydraulic or electric assist, vehicle design is typically constrained by the need to mount a rack and pinion gear system laterally across the vehicle, generally near the engine and transmission. This uses valuable space under the hood that designers would like to use for other purposes. However, conventional steering systems are robust and relatively fault-tolerant.
In steer-by-wire systems, the mechanical drive connection between the steering wheel and the steered vehicle wheels can be separated. Typically, the wheels are steered with an electric powered actuator according to an input signal obtained from a sensor that is associated with a steering wheel.
It is desirable to provide a system with some of the advantages of a steer-by-wire system while maintaining the simplicity and relatively fault-tolerant nature of a conventional steering system.
A hybrid steer-by-wire and mechanical steering system for a vehicle includes two subsystems. The first subsystem connects a steering wheel with a mechanical link adapted to turn a first wheel of the vehicle. The second subsystem has an electromechanical actuator adapted to turn a second wheel of the vehicle. An electronic controller adapted to receive information indicative of the positions of the steering wheel and the first wheel controls the electromechanical actuator to thereby control the position of the second wheel.